What's up with the UK and this topic? Not the literal OP topic, but seems like a weird obsession with hurting the progress of the trans community there, one of the more maligned and oppressed groups around.
It's mainly because of the high profile of a number of TERFs in the UK within media and twitter.
They are relatively small in terms of the amount of people that even know what the word TERF means, let alone actively are one, but their views are given a lot of credibility because they are already prominent members of the media or academics and as such get the 'benefit of the doubt' that they know what they're talking about. As such they normally get to spout their views in national press and spread their ideas quite far, albeit normally with clever language and sleights-of-hand. Then you slowly increase the rhetoric and make it more plain what your actually beliefs and intentions are, which is how we end up with articles like the BBC discussion about lesbians being pressured into sex with trans women that verge of the more 'mask off' side of this.
As for
why these people tend to be British, I think its largely due to a difference in the
evolution of feminism in the UK centre-left compared to America. Its an incredibly exclusive ideology that never really grappled with anything outside of the perspective of middle-class, white, university educated women and as such has quite a narrow view on the world and a whole host of issues.
In the eyes of some, they have successfully equated their views with 'feminism' and criticise any
reaction to them as innately misogynistic, something that a lot of usually right-minded people seem all too eager to gobble up. It's basically a warped version of what would be something we all agree with; the protection of women. They don't feel like they're attacking vulnerable people, they feel like they're defending women and this is the crux of it and why some (usually) well-meaning people are quite easily brought into defending people like Rowling. Because if you don't know what they're
really saying and you haven't been clued up on the issue, you just see a woman talking or writing about 'women's spaces' and getting 'attacked' for it.
For more general reading,
this interview with Judith Butler is always a good read and addresses TERFs within feminism directly but doesn't directly address it as a 'UK' issue.